The use of temporary fences made up of panels comprising pairs of uprights and stringers with infills of woven wire mesh, supported in concrete blocks, has become a common feature of building sites and other areas requiring temporary enclosure. In this arrangement, the anchor blocks are provided with one or more apertures into which the adjacent uprights or stiles of a pair of adjoining panels can be inserted.
To be effective in supporting the substantial weight of the fence panels and resisting the forces such as wind loading, which may be applied to them, the anchor blocks themselves must be of substantial size and weight, preferably at least 35 Kg. This places them outside the permitted maximum weight, which in some jurisdictions at least, may be lifted by a male person due to health and safety issues.
Two-part anchor blocks are known. Thus for example, a Dutch patent NL940155 discloses as one embodiment two interlocking anchor blocks arranged end to end; each block comprising a shell filled with concrete. A disadvantage of this arrangement is that each of the stiles of two adjacent fence panels is supported within one only of the pair of anchor blocks (when inserted into the central pair of apertures) so that with free sliding movement between the interlocking parts, there is likely to be reduced stability of the fence when subjected to lateral loading.
Another known two-part anchor block is disclosed in Australian patent application AU 2004208695. These blocks (also comprising plastic shells filled with concrete) are arranged side by side, with each block provided with a metal hoop; the two hoops located one above the other when the blocks are assembled, to form a rectangular aperture into which the adjoining stiles are inserted. It is only when a pair of adjoining uprights are inserted through the common aperture provided by these hoops that separation of the two parts of the block is prevented.
Apart from the complexity of manufacture, a particular disadvantage in use of this arrangement is that the panels at the ends of a temporary fence will be very poorly supported, since a single upright inserted through the aperture of the hoops, which are adapted to hold two uprights, will not be secured.
A further disadvantage of both the above disclosures of the prior art, lies in the fact that, particularly in the case of AU2004208695, the anchor blocks are unsuitable for acting as hinges or bearings when it is desired to operate one or a pair of panels of the temporary fence as an access gate.
Nor is there any provision in either of the pairs of anchor blocks of these prior art disclosures, for additional securing means; both relying purely on the mass of the blocks to maintain the fence in an upright position.
It is an object of the present invention to address or at least ameliorate some of the above disadvantages.